A primary concern in the operation of a pressurized water reactor (PWR) is the level of coolant within the reactor core vessel. A drop in coolant level which uncovers the core can result in significant damage to the core. Due primarily to the hostile environment within the reactor vessel, there is presently no device in use for direct measurement of the reactor core coolant level.
In the art, it has been the practice to infer the core coolant level from temperature and pressure measurements made external of the core in the core coolant loop. This method sometimes results in incorrect conclusions as to the coolant level in the core because measurements taken external to the reactor core do not necessarily reflect the core conditions. Clearly, there is a need for a direct means of measuring the coolant level in a liquid-cooled nuclear reactor core.